| Author |
Message |
Tolga Onbay
Guest
|
 Posted:
Fri Nov 18, 2005 1:15 am Post subject:
Beginner on DSP? |
|
|
I asked a question with subject "Voice Recorder?" a few days ago.
http://groups.google.com/group/comp.arch.embedded/browse_thread/thread/edfdae3e27e614f3
But I can't explain the question (again :) ) The Voice Recorder is a
part of my project on university. Actually I want to learn how voice is
inputted to MCU and how it is processed?
After that message, I searched the Internet again. I found some books
like The Scientist and Engineer's Guide to Digital Signal Processing
(http://www.dspguide.com). I'm going to process telephone quality
speech on MCU. In the book, for telephone quality speech sampling bit
rate is gaven as 8kHz, and number of bits is gaven as 8-bit on page
359(ch22) . I have questions on this :
1. If i process sounds on a 8 bit MCU like 8051, is there any loss of
voice or are there any disadvantages?
2. Do I have to use an Digital Signal Processor?
3. How much Clock Frequency do i need? Can i make it with a 40MHz MCU?
4. Can you advice me DSP books, if you think i have to learn it to make
this recorder?
Thanks again. I hope I could explain with this message :) |
|
| Back to top |
|
 |
Mark McDougall
Guest
|
| Posted:
Fri Nov 18, 2005 9:15 am Post subject:
Re: Beginner on DSP? |
|
|
Tolga Onbay wrote:
| Quote: | 1. If i process sounds on a 8 bit MCU like 8051, is there any loss of
voice or are there any disadvantages? 2. Do I have to use an Digital
Signal Processor? 3. How much Clock Frequency do i need? Can i make
it with a 40MHz MCU? 4. Can you advice me DSP books, if you think i
have to learn it to make this recorder?
|
This isn't really a signal *processing* problem - you're not actually
doing any processing of the voice data at all - simply sampling the data
and storing it, then playing it back again.
So I can't see why you'd need a DSP!
The quality of the voice is determined by two factors - the resolution
of the A/D conversion and the sampling rate.
The speed of the processor is, to a point, irrelevant. You just need to
ensure that the speed of the A/D converter is fast enough for your
desired sampling rate, and that your MCU has enough time to store
samples and setup for the next sample.
40MHz/8kHz = 5000 cycles. Assuming 4 cycles/instruction that's still
1250 instructions between samples. Plenty. Now you just need to check
the bandwidth of the A/D on this MCU.
Now you just have to worry about playback - D/A conversion. Plenty of
DACs avilable to do that, if your MCU hasn't got one.
Regards,
Mark |
|
| Back to top |
|
|
Richard Owlett
Guest
|
| Posted:
Fri Nov 18, 2005 4:09 pm Post subject:
Re: Beginner on DSP? |
|
|
Tolga Onbay wrote:
| Quote: | I asked a question with subject "Voice Recorder?" a few days ago.
http://groups.google.com/group/comp.arch.embedded/browse_thread/thread/edfdae3e27e614f3
But I can't explain the question (again :) ) The Voice Recorder is a
part of my project on university. Actually I want to learn how voice is
inputted to MCU and how it is processed?
After that message, I searched the Internet again. I found some books
like The Scientist and Engineer's Guide to Digital Signal Processing
(http://www.dspguide.com). I'm going to process telephone quality
speech on MCU. In the book, for telephone quality speech sampling bit
rate is gaven as 8kHz, and number of bits is gaven as 8-bit on page
359(ch22) . I have questions on this :
1. If i process sounds on a 8 bit MCU like 8051, is there any loss of
voice or are there any disadvantages?
2. Do I have to use an Digital Signal Processor?
3. How much Clock Frequency do i need? Can i make it with a 40MHz MCU?
4. Can you advice me DSP books, if you think i have to learn it to make
this recorder?
Thanks again. I hope I could explain with this message :)
|
I suggest posting to comp.dsp .
They are good at helping you define your question and then answering it. |
|
| Back to top |
|
|
Ulf Samuelsson
Guest
|
| Posted:
Mon Nov 21, 2005 1:15 am Post subject:
Re: Beginner on DSP? |
|
|
| Quote: | I asked a question with subject "Voice Recorder?" a few days ago.
|
I'm going to process telephone quality
| Quote: | speech on MCU. In the book, for telephone quality speech sampling bit
rate is gaven as 8kHz, and number of bits is gaven as 8-bit on page
359(ch22) . I have questions on this :
1. If i process sounds on a 8 bit MCU like 8051, is there any loss of
voice or are there any disadvantages?
2. Do I have to use an Digital Signal Processor?
3. How much Clock Frequency do i need? Can i make it with a 40MHz
MCU?
4. Can you advice me DSP books, if you think i have to learn it to
make this recorder?
Thanks again. I hope I could explain with this message :)
Go to www.avrfreaks.net
Select the "Tools" tab |
Select the "Tooltree" tab
Select the "Appnote" list item
Select the "I/O Applications"
Select the AVR335: Digital Sound Recorder with AVR and Serial
DataFlash
Download app note and code.
In order to use the AVR, you probably need to download the free tools:
* AVR Studio
* WinAVR
Links to both above can be found on www.avrfreaks.net. You need an AVR
programmer.
If you talk to your professor, he can request a free set of AVR tools
(Devboards/programmer + JTAG emulator) as part of the Atmel University
program.
Using onchip ADC gives you low quality voice.
For a high quality voice recorder, you want to have an external Voice
Codec.
Most MCUs does not have an appropriate interface to a voice codec.
The AT91SAM7S32 is a low end MCU which is based on the ARM core
which has a synchronous serial controller that can be interfaced to an I2S
codec.
| Quote: | If you have to use an 8051, then the AT89C51SND3 has an internal Codec
and interfaces to a large NAND flash.
The AT89C51SND1 and SND2 may also be useful. |
|
|
| Back to top |
|
|
|
|
|
|
FAQ
Memberlist
Register
Profile
Log in to check your private messages
Log in